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Coolant Leak At Back of Head

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Old 05-27-2015, 02:20 PM
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Coolant Leak At Back of Head

Hi folks. I posted this in my 260Z restoration thread but as the thread is getting long and wordy, I'm thinking that interest in that thread is getting kind of cursory and not all the right folk will pick up on this issue, hence a new thread.

I need some thoughts here.

I'm getting a slow coolant drip from the back of the motor where the head meets the block. I'm assuming for now it means a bad, or at least improperly installed head gasket.

Did some research and most folk are talking about blowing white smoke and such. I don't have symptoms like that. Motor was running a little "lopey" which at the time I thought could be my novice work on adjusting the carbs, but, maybe it's an indication of other head gasket problems - I don't know. What do y'all think?

Yes, I've been reading the FSM, other Z-related head gasket threads and so on, they're very informative. I've got a list of things to do now, one of which is to determine why the gasket is leaking and fix the root cause.

History on this motor is sparse, I don't know of any overheating issues from the most recent PO, however the most recent PO wasn't the original owner either.

Anyway, I'm preparing to pull the heads but first, someone stop me if they've seen this symptom and it's something else!
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Old 05-28-2015, 08:43 AM
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You could try retorquing the head. I had same issue, between 3-4 and on 6, slight coolant weep on the outside. Re-torqued the head, seems to be better. I just did a 4000 mile road trip with it through the Canadian Rockies and it didn't leak or have any issues. Honestly tho, I am going to pull the head, re-gasket, and new studs as soon as I can. Seems to be the best bet before she blows on the inside. Now with a re-torque you could run into issues snapping a bolt, which presents another deal of issues, and head coming off anyways! Since you are doing a full on thorough restoration, I would have no hesitation to pull the head, get it checked out, and new gasket with some studs!!

Last edited by Skully; 05-28-2015 at 08:47 AM.
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Old 05-28-2015, 10:31 AM
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Originally Posted by Skully
You could try retorquing the head.
That's exactly what I'm going to try today, thanks! Talked with the PO (my son-in-law) and he says that just before he abandoned work on the car, he had done a top-end overhaul of this motor. As such there's a new (well, not "new" but little used) gasket in there. What he didn't do was retorque it after running it for a bit because he never got the motor running well due to the old flat-top carbs.

I'm hoping that since it's now been through a bunch of warm-up cycles, this is all the problem is.

I'll be gentle with the retorque. Going to get a new torque wrench today as I don't trust the cheap Chinese one I have from Harbor Freight.

4,000 mile road trip eh? And through the Rockies too. Sounds awesome.

No wonder you've been off the net for a while.
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Old 05-28-2015, 12:24 PM
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Originally Posted by beg3yrs
That's exactly what I'm going to try today, thanks! Talked with the PO (my son-in-law) and he says that just before he abandoned work on the car, he had done a top-end overhaul of this motor. As such there's a new (well, not "new" but little used) gasket in there. What he didn't do was retorque it after running it for a bit because he never got the motor running well due to the old flat-top carbs.

I'm hoping that since it's now been through a bunch of warm-up cycles, this is all the problem is.

I'll be gentle with the retorque. Going to get a new torque wrench today as I don't trust the cheap Chinese one I have from Harbor Freight.

4,000 mile road trip eh? And through the Rockies too. Sounds awesome.

No wonder you've been off the net for a while.
I would for sure re-torque if it was a refreshed top!!

Yes sir just making my way home, the roads on the coast are to die for, these boring prairies are brutal :/.
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Old 05-28-2015, 05:18 PM
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Resolved - for now

Pulled off the valve cover and retorqued the head bolts. Turns out they were not replaced when son-in-law did the head overhaul and it was obvious. Some would turn OK but there were some that were a bit sticky.

The two at the back of the block seemed to be at the right torque but when I loosened them a quarter turn, they stuck and then jumped. I tightened them a bit and they stuck again. Decided since this was where the leak was I'd give it a bit more force and pop, they jumped and then began to tighten down in a more reasonable manner. Seems they never got fully tightened to begin with.

Tested the motor and voila, no more leak. We're good to go for now but will be mindful there are old bolts in the head. They'll get replaced when there's a reasonable opportunity.
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Old 05-28-2015, 07:11 PM
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I would doubt the quality of work when someone installs a used gasket. With a head kit you get valve stem seals, cam cover gasket and head gasket.
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Old 05-28-2015, 08:53 PM
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I guess what I wrote was little confusing. By "little used" I meant that the head gasket was installed new and then only had about 30 minutes of run time on it before the car was acquired by me a long time ago. It was not installed used, thank goodness as that's a great example of false economy.

Yes, a head kit was what used during the top end overhaul.

Last edited by beg3yrs; 05-29-2015 at 04:36 AM.
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